javascript - 如何将原型(prototype)附加到 JS 中的对象文字

Question

我试图理解 JavaScript 的原型(prototype)性质，并且我试图在不使用类构造函数的情况下创建对象继承。

如果 Cat 和 Dog 都是三个对象字面量，我如何将原型(prototype)链从 Animals 附加到它们？

此外，是否有一种方法可以执行 Object.create 并以文字形式添加更多属性(如 myCat)。

我添加了下面的代码并粘贴到 bin http://jsbin.com/eqigox/edit#javascript

var Animal = {
    name        : null,
    hairColor   : null,
    legs        : 4,

    getName : function() {
        return this.name;
    },
    getColor : function() {
        console.log("The hair color is " + this.hairColor);
    }
};

/* Somehow Dog extends Animal */

var Dog = {
    bark : function() {
        console.log("Woof! My name is ");
    }
};

/* Somehow Cat Extends Animal */

var Cat = {
    getName : function() {
        return this.name;
    },

    meow : function() {
        console.log("Meow! My name is " + this.name);
    }
};


/* myDog extends Dog */

var myDog = Object.create(Dog);

/* Adding in with dot notation */
myDog.name = "Remi";
myDog.hairColor = "Brown";
myDog.fetch = function() {
    console.log("He runs and brings back it back");
};


/* This would be nice to add properties in litteral form */
var myCat = Object.create(Cat, {
    name        : "Fluffy",
    hairColor   : "white",
    legs : 3, //bad accident!
    chaseBall : function(){
        console.log("It chases a ball");
    }

});

myDog.getColor();

Answer 1

您可以使用 Object.create 将您定义的对象用作原型(prototype)。例如:

var Dog = Object.create(Animal, {
    bark : {
        value: function() {
            console.log("Woof! My name is " + this.name);
        }
    }
});

现在您可以创建一个新的 Dog 对象:

var myDog = Object.create(Dog);
myDog.bark();  // 'Woof! My name is null'
myDog.getColor();  // 'The hair color is null'

示例:http://jsfiddle.net/5Q3W7/1/

或者，如果您在没有 Object.create 的情况下工作，您可以使用构造函数:

function Animal() {
    this.name = null;
    this.hairColor = null;
    this.legs = 4;
};

Animal.prototype = {
    getName : function() {
        return this.name;
    },
    getColor : function() {
        console.log("The hair color is " + this.hairColor);
    }
}

function Dog() {
}

Dog.prototype = new Animal;
Dog.prototype.bark = function() {
    console.log("Woof! My name is " + this.name);
};

示例:http://jsfiddle.net/5Q3W7/2/

有关 Object.create 的更多信息:https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/Object/create/

有关构造函数和原型(prototype)链的更多信息: https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/Object/constructor

https://developer.mozilla.org/en/JavaScript/Guide/Inheritance_and_the_prototype_chain